Plastic bags, that is bags formed of thermoplastic synthetic resin film, for example polyethylene, have come into common usage as produce bags, grocery bags, general and specialty merchandise bags, and the like. Such bags are produced in a variety of configurations and constructions with one of the most widely known forms of bag being what is usually referred to as a T-shirt bag. The T-shirt bag is normally formed with a pair of side gussets and includes a pair of laterally spaced upwardly extending handles with a transverse bag mouth therebetween. Other conventional forms of handle bags include bags with central extending handles and bags with handles defined by cutouts through the front and rear walls of the bag. The bags may be partitioned into multiple chambers as in U.S. Pat. No. 4,696,403, issued Sept. 29, 1987, and commonly assigned with this application, or may comprise flat ungusseted bags with no handles as frequently found at produce stands.
While plastic bags have significant advantages over conventional paper bags for supporting produce, groceries and the like, and thus have found wide acceptance in the marketplace, one particularly vexing problem with regard to the use of such bags is the difficulty in opening the bag mouth. This difficulty is a direct result of several factors arising from the nature of the material itself and the manner in which the bag is formed. For example, "static cling" is invariably present between the extremely thin film sheets of the individual bags. Further, there is a tendency for the film sheets to stick as a result of additives and other chemicals migrating to the surface of the plastic film. Adhesion between the bag sheets also frequently arises as a result of the actual cutting operation which defines the bag mouth, producing, for example, a weak cold welding of the sheet edges together.
In each case, while the sheets at the bag mouth are separable, there are inherent difficulties in obtaining an initial sufficient grip on the sheets to overcome the natural tendency of the mouth of the bag to remain closed and to effect the desired opening of the bag mouth. This is the situation regardless of whether the bag is severed from a pack or roll, or provided as a separated bag.